Boiler and injector for reducing the concentration of pollutants in an effluent

ABSTRACT

A process and apparatus for reducing the concentration of pollutants in an effluent from the combustion of a fuel or waste material is presented. The process and apparatus enables injection of an effluent treatment fluid at low treatment fluid flow rates yet provides an even dispersion of treatment fluid within an effluent passage with little or no clogging. An atomization conduit, positioned coaxially within a treatment fluid supply conduit, extends into the effluent and supplies an atomization fluid, such as steam or air. A treatment fluid is supplied through a supply conduit and through at least one jet in the atomization conduit wall at a velocity of between 2-60 feet per second, causing atomization of the treatment fluid within the nozzle.

This is a continuation of co-pending application Ser. No. 07/160,684filed on Feb. 26, 1988, no abandoned.

TECHNICAL FIELD

The present invention relates to the reduction of pollutants, such asnitrogen oxides in an effluent, generated by the combustion ofcarbonaceous fuels and waste materials. More particularly, thisinvention relates to a process and injector therefor.

BACKGROUND OF THE INVENTION

An effluent treatment system designed for maximum pollutant removal willuse a staged injection system in which treatment fluids are injected atseveral different points in the path of the combustion effluent. This isdisclosed in commonly owned U.S. patent applications Ser. No. 022,716 toEpperly, Peter-Hoblyn, Shulof and Sullivan, entitled "Multi-StageProcess for Reducing the Concentration of Pollutants in an Effluent,"now issued as U.S. Pat. No. 4,777,024, and Ser. No. 050,198, filed May14, 1987 in the name of Epperly, O'Leary and Sullivan and titled"Process for Nitrogen Oxides Reduction and Minimization of theProduction of Other Pollutants," now issued as U.S. Pat. No. 4,780,289,the disclosures of which are hereby incorporated by reference. Eachstage will have different treatment fluid requirements as the pollutantconcentration and effluent temperature varies as the effluent progressesthrough the combustion chamber and past several heat exchangers. Eachstage of a treatment system requires a treatment fluid and treatmentfluid injector appropriate for the treatment fluid flow rate and theconditions of the combustion chamber.

A particular problem encountered in designing injector systems forcertain locations is providing a uniform distribution of treatment fluidacross the path of the effluent. In a typical retrofit application, aninjector should be able to generate droplets in a selected size rangeand distribute them uniformly across the boiler cross-section.

Uniform distribution of treatment fluid is most difficult to achievewhere relatively low flow rates of treatment fluid are being injected,for example, in the third or fourth stage of a treatment system, wherethere may be fewer pollutants in the effluent stream. In this situation,it is necessary to contact a sufficient amount of treatment fluid withall of the effluent to reduce the pollutants, yet not to saturate even aportion of the gas stream with chemicals which could increase thepollutant level instead of reacting with the pollutants to reduceemissions. For example, a urea treatment fluid if injected in excessivequantities can cause excessive ammonia in the effluent stream. In priorart injectors such as a pin jet injector used to provide highpenetration by a small jet of chemicals at low treatment fluid flowrates there can be a poor dispersion of the treatment fluid across theeffluent path and particularly near the effluent passage wall from whichthe injector extends.

The problems facing the successful method and apparatus for injectingsuch compositions into an effluent are many. For instance, the heat ofthe effluent can readily cause a loss in structural integrity of mostnozzles or their supports. When the composition to be injected is asolution, often precipitated solute will collect at the end of thenozzle and can plug the nozzle. A plugged nozzle on a treatment fluidinjector is not merely an inconvenience: such plugging can render atreatment system ineffective, such that the combustion system does notcomply with environmental regulations, necessitating the shut down ofproduction facilities and the loss of time and money. Furthermore, theprecipitated solute can break off as chunks and damage the interior ofthe boiler. Variability of droplet size, degree of dispersion and depthof penetration must be provided for by an injector, depending on theboiler configuration or boiler load. These problems have not beensuccessfully addressed by the prior art.

The prior art relating to injection apparati and nozzles shows that suchinjection apparati are usually designed for a specific fluid andenvironment of use. Typically, the prior art teaches mixing of a liquidwith an atomizing fluid at or near a nozzle tip, with the liquid beinginjected into the atomizing fluid at a point concentric within theatomizing fluid conduit. This external mixing of a liquid andatomization fluid can reduce clogging problems. However, this type ofdesign does not allow for deep penetration of a broad band of dropletsizes into a chamber at low liquid flow rates. For example, U.S. Pat.No. 1,625,098, to Rudolph, (an atomizing cleaner) U.S. Pat. No.3,876,150 to Dwyer (a paint spray nozzle) and U.S. Pat. No. 1,965,465 toMagowan (a liquid fuel burner) show this type of injector layout.

An internal mix injector nozzle, in which a liquid contacts an atomizingfluid before exiting from the nozzle tip, can give a finer control overpenetration at low liquid flow rates. However, commercially availableinternal mix injector nozzles are extremely prone to rapid clogging in acombustion chamber application due to the precipitation of treatmentchemicals in the nozzle.

The prior art thus does not teach an injector apparatus suitable forheavy duty use as in a combustion chamber and effluent passage, andwhich is useful for uniform delivery at low treatment fluid rates in aprocess for treating pollutants in an effluent stream.

There exists a present need, therefore, for an injection apparatus forinjecting a treatment fluid, e.g., an aqueous solution of a NO_(x)reducing composition into an effluent of the combustion of acarbonaceous fuel, which provides both good dispersion and penetrationof injection fluid, and which reduces or eliminates plugging problems inan injector.

DISCLOSURE OF INVENTION

A process and injector apparatus for reducing the concentration ofpollutants, such as nitrogen oxides, in an effluent from the combustionof a carbonaceous material is presented. The process comprises:positioning an injector within an effluent passage, where the injectorincludes an atomization conduit having an injector nozzle and at leastone jet penetrating the wall of the atomization conduit upstream of thenozzle, and a supply conduit; supplying through the supply conduit andthrough the at least one jet an effluent treatment fluid; and supplyinga carrier and atomization fluid through the atomization conduit toinject the solution into the effluent passage and preferably to effectfurther atomization of the solution prior to injection.

Preferably, the supply conduit is coaxial with and disposed around theatomization conduit. The at least one jet is preferably located upstreamof the nozzle end at a distance equal to up to about thirty-two timesthe inner diameter of the atomization conduit, and most preferably at adistance equal to about five to sixteen times the inner diameter of theatomization conduit. Preferably there are two or more of such jets andmost preferably there are two jets. The treatment fluid preferablycomprises an acqueous solution of urea, ammonia, nitrogenatedhydrocarbon, oxygenated hydrocarbon, hydrocarbon or combinationsthereof.

The injector apparatus comprises: (a) means for providing an atomizationfluid, having a nozzle for extending into an effluent passage; (b) meansfor supplying an effluent treatment fluid to the effluent passage, and(c) the treatment fluid supplying means being connected to theatomization fluid providing means by at least one jet upstream of thenozzle.

Preferably, the means for providing an atomization fluid comprises anatomization conduit and the at least one jet penetrates the wall of theatomization conduit. The means for supplying an effluent treatment fluidpreferably comprises a supply conduit coaxial with and disposed aroundthe atomization conduit. There are preferably two or more such jets,each being located in the atomization conduit upstream of the nozzle ata distance equal to up to about thirty-two times the inner diameter ofthe atomization conduit, and most preferably at a distance equal toabout five to sixteen times the inner diameter of the atomizationconduit. Most preferably, the two jets are oriented such that thetreatment fluid streams entering the atomization conduit impinge on eachother, further enhancing droplet formation. The atomization fluid ispreferably provided in a flow of between about 200 to about 800 feet persecond, and the effluent treatment fluid is supplied through the jets ata velocity of between about two to about sixty feet per second.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood and its advantages moreapparent in view of the following detailed description, especially whenread with reference to the appended drawings, wherein:

FIG. 1 is an installation schematic in perspective, partially brokenaway, of the apparatus of the present invention disposed in a utilityboiler;

FIG. 2 is a side elevation view, partially broken away of the apparatusof the present invention;

FIG. 3 is a cross-sectional view of the apparatus of the presentinvention taken across line 3--3 of FIG. 2;

FIG. 4 is a front end view of the supply and atomization conduits of thepresent invention;

FIG. 5 is a side elevation view of an alternate embodiment of theapparatus of the present invention; and

FIG. 6 is a front cross-sectional view, taken along line 6--6 of FIG. 5.

As used herein, the term "front" refers to the end of the apparatuswhich extends into the effluent; the term "rear" refers to the end ofthe apparatus from which the fluids and solutions may be supplied.Although this description is written in terms of the reduction of thenitrogen oxides concentration in an oxygen-rich effluent, it will berecognized that the apparatus of the present invention is equallyapplicable to any situation requiring the injection of an atomized fluidinto a high temperature environment. Moreover, it will further berecognized that some or all of the figures are schematic representationsfor purposes of illustration and do not necessarily depict the actualrelative sizes or locations of the elements shown.

BEST MODE FOR CARRYING OUT THE INVENTION

The process and apparatus of the invention enable reduction of theconcentration of nitrogen oxides, or other pollutants, in effluents fromthe combustion of a carbonaceous materials, including fuel per se andwaste materials. Representative fuels are fuel oil, gas, coal, ligniteand the like.

As illustrated in FIGS. 1-4 the apparatus 20 of this invention comprisesa injector 21 comprising a supply conduit 30 which is operable to supplyand inject a treatment fluid, such as a solution, through an annularspace 32 into a high temperature environment, such as the effluentstream of a utility boiler 60. Supply conduit 30 may be any suitableconduit for this purpose and is advantageously a seamless tube of atemperature and corrosion resistant material such as a metal, especiallytemperature-resistant stainless steel. The treatment fluid to beinjected through supply conduit 30 is supplied by any conventionalsupply or pumping device (not shown), as would be familiar to theskilled artisan, and is preferably supplied through a metering device toallow careful control of the amount to fluid injected. For example,treatment fluid may be supplied by valve 34 to fitting 36 having apressure gauge 38 for monitoring the treatment fluid delivery pressure.

Injector 21 of this invention further comprises an atomization conduit40, as illustrated in FIG. 3, for supply of a carrier and atomizationfluid therethrough. Atomization conduit 40 may be any suitable conduitoperable to supply atomization fluid and is advantageously a seamlesstube of a temperature resistant material such as a metal, especiallytemperature-resistant stainless steel. The carrier and atomization fluidto be supplied through atomization conduit 40 may be any fluid operableto act as a carrier for treatment fluid droplets and preferably to causeatomization of the treatment fluid supplied through supply conduit 30.Supply conduit 30 is preferably coaxial with and disposed aroundatomization conduit 40, although the invention may also be practicedusing separate, non-concentric conduits.

At least one jet 42 penetrates the walls of atomization conduit 40 forfeeding treatment fluid to space 43 in the atomization conduit 40 fromthe supply conduit 30. Preferably there are two or more such jets 42.Most preferably there are two such jets 42 located on opposite sides ofatomization conduit 24. In the preferred embodiment, jets 42 are locatedsuch that the streams of treatment fluid impinge on each other in space43. Although jets 42 are shown as simple orifices in the walls ofatomization conduit 40, it is to be understood that jets 42 may be anytype of communicating conduit between supply conduit 30 and atomizationconduit 40.

Atomization is primarily a function of velocity of the treatment fluidas it passes through the jets 42. Atomization is enhanced by locatingjets 42 so that treatment fluid streams passing therethrough impinge oneach, and further by the force of atomization fluid contacting thetreatment fluid as it exits from jets 42. The velocity of treatmentfluid through jets 42 can be varied by using jets of different sizes, byvarying the pressure of the treatment fluid supplied to the jets 42 andby varying the flow rate of the atomization fluid. The force ofatomization fluid contacting the treatment fluid can be varied byvarying the flow of atomization fluid through atomization conduit 40,for instance by means of valve 44.

Typically, the carrier and atomization fluid is steam or a gas, such asair, which is supplied to atomization conduit 40 from conventional means(not shown) through, illustratively, valve 44 and fitting 46, the flowof which may be measured by gauge 48. Most preferably, the atomizationfluid is steam. The atomization fluid is preferably provided at a gaugepressure of about five to about twenty pounds per square inch at flowrates from about 200 to about 800 feet per second. The treatment fluidis advantageously supplied at a flow rate and pressure which is higherthan that of the pressure in the atomization conduit, and should besupplied at a pressure sufficient to produce a flow of treatment fluidthrough jets 42 at a velocity of between about two to about sixty feetper second; usually the treatment fluid will be supplied at a gaugepressure of about 10 to about 100 pounds per square inch. At thisvelocity, atomization of the treatment fluid takes place immediatelyupon introduction into the atomization conduit 40. Atomization isenhanced if the jets 42 are located so that the streams of treatmentfluid passing through jets 42 impinge on each other. The carrier andatomization fluid also enhances atomization when supplied at highervelocities.

The carrier and atomization fluid will preferably project at least aportion of the droplets of treatment fluid to a distance of at leastabout 75% of the width of the flue gas passage at the point ofinjection, as illustrated in FIG. 1. Where it is feasible to positioninjectors on two sides of the flue gas passage, it is preferable thatthe injection extend only to about 50% of the width of the flue gaspassage.

In selecting the size of jets 42, the practitioner must provide a jetlarge enough to allow a sufficient flow of treatment fluid to treat theeffluent, and small enough so that the fluid velocity will be in therange of about two to about sixty feet per second. It has been foundthat for 1/2 inch diameter atomization conduit having a 3/8 inch innerdiameter, that the diameter of jets 42 should be in the range of about1/32 to about 1/4 inch.

The dispersion of treatment fluid throughout the effluent is a functionof the distance of the jets 42 to the nozzle tip 41 and of the force ofthe atomization fluid contacting the treatment fluid as it exits thejets 42. For example, a narrow dispersion may be obtained by locatingjets 42 upstream of the nozzle tip 82 at a distance X equal to aboutthirty-two times the inner diameter of the atomization conduit 40. Thisjet to nozzle distance provides a narrow stream of treatment fluidsimilar to that provided by a pin jet; the depth of penetration of thestream can be varied by varying the atomization fluid flow rate. Ifdistance X is selected to be equal to about sixteen times the innerdiameter of the atomization conduit 40, a spray pattern in still airwhich has a conical first spray section adjacent the nozzle consistingprimarily of small droplets and a cylindrical second spray sectionfurther away from the nozzle consisting of larger droplets is provided.A very broad spray pattern with a short travel is obtained by locatingjets 42 adjacent to the nozzle tip 41.

If desired by the practitioner, as illustrated in FIG. 3, injector 21 ofthis invention may be provided with alignment tabs 23 to maintainatomization conduit 40 centrally disposed within supply conduit 30.Alignment tabs 23 may be placed intermittently along the length ofatomization conduit 40. Alignment tabs 23 are preferably disposed oneither the inside of supply conduit 30 or, more preferably, the outsideof atomization conduit 40 and are advantageously attached by welding.

In an alternate embodiment 120 of this invention, injector 121 isprovided with a cooling conduit 150 disposed outside of and around aportion of supply conduit 130. An appropriate cooling fluid such as air,water or steam may be circulated in annular space 158, to maintain thecooling of both atomization and supply conduits 140 and 130 in the hightemperature environment of a boiler. Cooling fluid may be supplied tocooling conduit 150 from a suitable source (not shown) through,illustratively, appropriate valve 154 and fitting 156, and measured bygauge 158, as would be familiar to the skilled artisan. As desired,alignment tabs 154 may also be provided between atomization conduit 130and cooling conduit 150 as illustrated in FIG. 6.

A significant advantage of this invention is that injector may provide abroad dispersion of droplets, i.e., a fog, as well as providing a rangeof droplet sizes. In addition, the flow of atomization fluid serves toprevent any particles from precipitating from the treatment fluid andcollecting in the atomization conduit 40 where they might clog injector21 and/or break off as a chunk and cause damage to the inside of boiler10. The flow of atomization fluid also serves to cool supply conduit 30to reduce the chances of supply conduit failure.

The treatment fluid to be injected typically comprises a solution havingat least one additive compound effective in reducing NO_(X) and/orSO_(X) under the conditions of injection. The temperature of theeffluent at the point of injection, the concentration of the additivecompound in the solution, and the size of the droplets in thedispersion, are selected to achieve reduction in nitrogen oxide or otherpollutant levels in the effluent. The invention provides for treatinghigher temperature effluents, in the range of about 1350° F. to about2200° F. by injecting an urea, ammonia or a nitrogenated hydrocarbontreatment solution, such as those disclosed and described in commonlyassigned U.S. patent application Ser. No. 784,826 filed Oct. 4, 1985 inthe name of Bowers and entitled "Reduction of Nitrogen and Carbon-BasedPollutants Through the Use of Urea Solutions", and in commonly assignedU.S. patent application, Ser. No. 906,671, filed Sept. 10, 1986 in thename of Bowers and entitled "Reduction of Nitrogen-and Carbon-BasedPollutants Through the Use of Urea Solutions Containing OxygenatedHydrocarbon Solvents", now issued as U.S. Pat. No. 4,751,065, and incopending and commonly assigned U.S. patent application Ser. No.039,013, filed Apr. 15, 1987 in the name of Sullivan and Epperly andtitled "Process for the Reduction of Nitrogen Oxides in An EffluentUsing A Hydroxy Amino Hydrocarbon now issued as U.S. Pat. No.4,803,059", and in copending and commonly owned U.S. patent applicationSer. No. 100,128, filed Sept. 23, 1987 in the name of Epperly, Sullivanand Sprague and titled "Process for the Reduction of Nitrogen Oxides InAn Effluent", and in U.S. patent application Ser. No. 090,962, filedAug. 28, 1987 in the name of Epperly, Sullivan & Sprague and titled"Process for the Reduction of Nitrogen Oxides in an Effluent" thedisclosures of which are all incorporated by reference. In addition,such solutions may also include an enhancer such ashexamethylenetetramine and/or ethylene glycol and/or an oxygenatedhydrocarbon as taught by commonly assigned U.S. patent application Ser.No. 811,532, filed in the name of Bowers on Dec. 20, 1985, and titled"Reduction of Nitrogen- and Carbon-Based Pollutants", now issued in acontinuing application as U.S. Pat. No. 4,751,065 and U.S. patentapplication No. 014,431, filed Feb. 13, 1987 in the name of Epperly etal. and entitled "Process for the Reduction of Nitrogen Oxides in anEffluent", now issued as U.S. Pat. No. 4,770,863 and U.S. Pat. No.4,719,092 to Bowers; the disclosures all of which are incorporatedherein by reference in their entireties. Another embodiment of theinvention provides for treating lower temperature effluents, in therange of about 800° F. to about 1400° F. by injecting a hydrocarbon,such as ethylene glycol, furfural or hydrogen peroxide, as taught bycommonly owned and copending U.S. patent application No. 022,799, filedon Mar. 6, 1987 in the name of Sullivan and titled "Process for ReducingNitrogen Oxides in an Effluent Using a Hydro-carbon or HydrogenPeroxide", the disclosure of which is hereby incorporated by reference.

The concentration of the additive compound or compounds within theeffluent should be sufficient to provide a reduction in nitrogen oxide,sulfur oxide, or other designated pollutants. Typically, in the case ofa urea, ammonia, or nitrogenated hydrocarbon solution for loweringNO_(x), the active compound will be employed at a molar ratio ofnitrogen in the additive compound to the baseline nitrogen oxide levelin the effluent of about 1:10 to 5:1, and will more preferably be withinthe range of about 1:4 to 3:2. In the case of a hydrocarbon solution,the active compound will be employed to provide a weight ratio ofhydrocarbon in the treatment fluid to the nitrogen oxide level in theeffluent of about 0.05:1 to about 25:1. The exact concentration of thiscomponent, however, will depend upon the overall economics of theprocess, and must further take into account the size of the droplets,the ability of the injector to uniformly disperse the droplets, and thelife of the droplets within the effluent under the high temperatureconditions existing therein.

When sulfur-containing fuels are burned, and the effluent is treatedwith urea for NO_(x) reduction, it is important to reduce the level ofammonia in the final effluent by employing an oxygenated material,especially an oxygenated hydrocarbon, preferably as part of the ureasolution as taught in copending and commonly assigned U.S. patentapplication, Ser. No. 784,828, filed Oct. 4, 1985, the disclosure ofwhich is incorporated herein by reference in its entirety. Free ammoniamay otherwise react with the sulfur-containing combustion products toproduce ammonium sulfate and/or bisulfate which precipitate as a solidand can rapidly reduce the efficiency of the heat exchange apparatusassociated with the boiler; furthermore, any unreacted ammonia is itselfan undesirable effluent component.

The injector of the present invention is particularly useful in treatinglower temperature effluents in the range of about 800° F. to about 1400°F. using a hydrocarbon or oxygenated hydrocarbon treatment fluid asdisclosed in U.S. patent application No. 022,799.

Aqueous solutions are typical due to their economy and can be employedwith suitable effectiveness in many situations. The effective solutionswill vary from saturated to dilute. While water will be an effectivesolvent for most applications, there are instances where other solventsmay be advantageous in combination with water.

The treatment fluid should be dispersed uniformly within effluent streamat a point where the effluent is at a temperature effective forpollutant reduction employing the desired additive at a particularconcentration and droplet size.

Preferably, treatment fluid is injected at a number of spaced positionsin a manner effective to uniformly form and disperse droplets oftreatment fluid within the flowing effluent stream to achieve uniformmixing.

The use of the process and apparatus of the present invention in amultistage effluent treatment system is shown in the following example:

EXAMPLE 1

A utility boiler, shown schematically in FIG. 1, as 60, is fired withbrown coal at a supply rate equal to about 145 MW of generatedelectricity, with an excess of oxygen of 7%. A flue gas monitor 62having a probe located adjacent the exit of the effluent passagemeasures the concentration of pollutants in the effluent.

An injector 21 of the present invention, comprising: an atomizationconduit having a 1/2 inch diameter and a 3/8 inch inner tube diameter,with two jets 42 each 1/8 inch in diameter penetrating the atomizationconduit six inches upstream of the nozzle tip 41, and a supply conduithaving an inner diameter of 3 inches coaxial with and disposed aroundthe atomization conduit, is inserted through a port in the boiler wall.The injector is inserted such that the nozzle end 21 extends about 12inches into the interior of the effluent passage. The point of insertioncorresponds to that shown in FIG. 1, downstream of boiler tubes 66,where the temperature is determined to be 1184° F.

A treatment fluid comprising a mixture of ethylene glycol and molassesis prepared and injected through the injector of the present invention,using air as an atomization fluid supplied at the rate of about 14 SCFM,as determined by a flow meter, at a velocity of about 470 feet persecond. The treatment fluid is provided at a rate of about 200 gallonsper hour and passes through jets 42 at a linear velocity of about 44feet per second.

The spray pattern of the injected solution shows a conical first sectionhaving a dispersion angle of about 20 degrees and which extends forabout five feet from the tip of the nozzle into the effluent passageway,and a cylindrical second section which extends beyond the first conicalsection to about five feet. The NO_(X) concentration in the effluent isreduced from 120 to 107 ppm, a reduction of 11%.

While a preferred embodiment of the present invention has been describedabove and illustrated in the accompanying drawings, it is understoodthat other embodiments are within the contemplation of the inventor andthe invention is not limited to the embodiments shown. In particular,the present invention may be used to treat effluents in high temperatureand high pollutant zones as well as in lower temperature and lowerpollutant zones.

I claim:
 1. A boiler for the combustion of a carbonaceous fuel, saidboiler comprising:(a) a combustion chamber; (b) a passage extending fromsaid combustion chamber, said passage capable of containing an effluentfrom the combustion of a carbonaceous fuel; (c) an injector apparatusfor supplying an atomized treatment fluid into said passagecomprising:(i) an atomization conduit having an injector nozzle at oneend thereof extending into said passage; (ii) at least one jetpenetrating the wall of said atomization conduit upstream of said nozzleat a distance equal to about sixteen to up to about thirty-two times theinner diameter of said atomization conduit; (iii) a supply conduit forsupplying an effluent treatment fluid to said at least one jet, saidsupply conduit being coaxial with and disposed around said atomizationconduit; (d) means for supplying a flow of atomization fluid in saidatomization conduit at a velocity of about 200 to about 800 feet persecond; (e) means for supplying said effluent treatment fluid throughsaid supply conduit, and through said at least one jet at a velocity ofbetween about two to about sixty feet per second.
 2. A boiler accordingto claim 1 wherein there are two said jets, and wherein said two jetsare located upstream of said nozzle at a distance equal to about five toabout sixteen times the inner diameter of said atomization conduit.
 3. Aboiler according to claim 1 wherein said at least one jet has a diameterin the range of about 1/32 to about 1/4 inch.
 4. A boiler according toclaim 1 wherein there are two or more of said jets located so thattreatment fluid streams passing therethrough impinge on each other.
 5. Aboiler for the combustion of a carbonaceous fuel, said boilercomprising:(a) a combustion chamber; (b) a passage extending from saidcombustion chamber, said passage capable of containing an effluent fromthe combustion of a carbonaceous fuel; (c) an injector apparatus forsupplying an atomized treatment fluid into said passage comprising:(i)an atomization conduit for supplying atomization fluid to said passage,said atomization conduit having an injector nozzle at one end thereofextending into said passage; (ii) a supply conduit for supplying aneffluent treatment fluid to said atomization conduit, said supplyconduit being coaxial with and disposed around said atomization conduit;(iii) at least one jet penetrating the wall of said atomization conduitand connecting said supply and atomization conduits upstream of saidnozzle at a distance equal to about sixteen times the inner diameter ofsaid atomization conduit; (iv) means for providing said atomizationfluid to said atomization conduit at a velocity in the range of about200 to about 800 feet per second; and (v) means for supplying saidtreatment fluid to said supply conduit such that said treatment fluidpasses through said at least one jet at a velocity of between about twoto about sixty feet per second;whereby a spray of effluent treatmentfluid having a conical first spray section and a cylindrical secondspray section is provided from said nozzle.
 6. A boiler according toclaim 5 wherein said conical first spray section comprises smalldroplets and said cylindrical second spray section comprises largerdroplets.
 7. A boiler according to claim 5 wherein there are two saidjets, said jets having a diameter in the range of about 1/32 to about1/4 inch.
 8. A boiler according to claim 5, wherein said boiler furthercomprises a cooling conduit coaxial with and disposed around saidatomization and supply conduits.
 9. A boiler according to claim 5,wherein said effluent treatment fluid comprises as an additive urea,ammonia, or a nitrogenated hydrocarbon.
 10. A boiler according to claim9, wherein said effluent treatment fluid further comprises as anadditive hexamethyenetetramine or an oxygenated hydrocarbon.
 11. Aboiler according to claim 5, wherein said effluent treatment fluidcomprises as an additive a hydrocarbon.
 12. A boiler according to claim11, wherein the temperature of said effluent in said passage is belowabout 1400° F.